FWIW I did follow the break-in somewhat closely(ish). For the first tank and a half I kept it under about 20mph, but wasn't afraid of going WOT up hills and whatnot, just not over 20. Going WOT up hills is going to help the rings seal better to the cylinder wall. But no high RPM to hurt bearings, etc. After 2 tanks I switched from 24:1 oil mixture to 36:1. I never did 16:1, that's if you're running 30 weight engine oil in the gas.
After probably 500 miles I switched to synthetic oil and 50:1 mixture which gave me a performance boost.
Now with well over 3000 miles on the engine, it has no issues at all. I'm running a slant head, I've filed it down a bit for even higher compression, and everything is great! Still just as high compression as ever, no bad bearing sounds, just smooth running.